Underwater photo contests to complement coastal fish inventories: results from two Mediterranean Marine Protected Areas

Marine Protected Areas (MPAs) are particularly useful to assess fish assemblages and to obtain reliable fish inventories. In this study we demonstrate the value of underwater photo contests as complementary tools to achieve these goals. We examined 3513 underwater pictures taken by free divers and scuba divers participating in two photo contests organized by the Italian Federation of Sport Fishing and Underwater Activities (FIPSAS). The competitions were held in the Italian MPAs of Punta Campanella (Tyrrhenian Sea; 2017) and Capo Rizzuto (Ionian Sea; 2018). Altogether, 97 fish species, 89 at Punta Campanella and 75 at Capo Rizzuto, were identified in different coastal habitats (depth range, 0-19 m). Their number was considerably higher than the one obtained with other census techniques and was close to the maximum number of species described at the two locations, as shown by accumulation curves. Significant differences in species richness were demonstrated at the level of both location and habitat type. The reasons for such differences are discussed along with the advantages and limitations of underwater photo contests as a participatory tool to obtain regular updates on coastal fish inventories in MPAs and in wider areas.